Time for them to move from the dark side.. and to what is provided and supported by your company..
They've been told that if a Dell is what they want the a Dell is what they shall have. So we now have a windows laptop as part of the estate
I would not bring a Windows device into the fold for a single user, the cost and training to manage and secure that single device is not worth it to keep one user happy.
Your most direct equivalent to Jamf Now and Jamf Protect, would be Microsoft Intune and Microsoft Defender. You would probably want to work through an MSP for licensing, and possibly management of the device as well unless you have someone versed in managing Windows already.